The VERB is the action that takes place in the sentence. The SUBJECT is who or what is doing the action described by the verb. Verbs in English often change their form depending on the subject of the sentence. This can be confusing to people who are trying to learn English. Example: I AM trying to improve my English. My brother IS trying to improve his English. My friends ARE trying to improve their English. As you can see in the examples, the verb (AM, IS, ARE) had to change to agree with the subject of the sentence. Hope this helps!

It means that the subject and the verb must match. For example: The girl eat a sandwich - This is not good as the verb doesn't match the third person subject. It should be: The girl eats a sandwich.